Gene therapy is the most promising treatment for many acquired and genetic diseases. Its full potential has not been realized due to the inadequate efficiency of DNA delivery. Non-viral vectors are synthetic vehicles which are void of most problems caused by viruses, but also lack many of their desirable properties (efficient cellular uptake, endosomal release, directional cytoplasmic movement, disassembly and nuclear delivery of the genome). If artificial gene delivery particles could mimic such virtues, those would greatly improve their performance. During the proposed Phase I studies novel cationic polymers will be synthesized and used for the formation of a variety of condensed DNA particles. The particles will then be modified by using two technologies previously developed by Mirus: recharging the surface to obtain negative zeta potential, yet maintaining fully condensed DNA, and caging the particles to prevent their aggregation. Particles with near-neutral surface will also be created. Their Stability will be assessed in physiological buffers and cytosolic extracts, and also in the cytoplasm of microinjected cells. PROPOSED COMMERCIAL APPLICATION: The nuclear transport technology developed in the proposed studies will be incorporated into gene therapy vectors that contain ligands for cellular receptors and endosomolytic agents. Given that the non-viral vector industry realizes the importance of the nuclear transport hurdle, technology for overcoming this hurdle will have great commercial value.